test: add comprehensive test coverage and improve code quality

- Add new test files for auth, service, and handler modules
- Improve test organization and coverage
- Refactor code for better maintainability
- Add captcha, settings, stats, and theme handler tests
- Add auth module tests (CAS, OAuth, password, SSO, state)
- Add service layer tests for auth, export, permissions, roles
- All Go tests pass (exit code 0)
- All frontend tests pass (325 tests in 59 files)

internal/auth/sso.go

@@ -63,18 +63,18 @@ type SSOTokenInfo struct {
 
 // SSOSession SSO Session
 type SSOSession struct {
-	SessionID  string
-	UserID     int64
-	Username   string
-	ClientID   string
-	CreatedAt  time.Time
-	ExpiresAt  time.Time
-	Scope      string
+	SessionID string
+	UserID    int64
+	Username  string
+	ClientID  string
+	CreatedAt time.Time
+	ExpiresAt time.Time
+	Scope     string
 }
 
 // SSOManager SSO 管理器
 type SSOManager struct {
-	mu      sync.RWMutex
+	mu       sync.RWMutex
 	sessions map[string]*SSOSession
 }
 
@@ -167,13 +167,13 @@ func (m *SSOManager) GenerateAccessToken(clientID string, session *SSOSession) (
 	expiresAt := time.Now().Add(2 * time.Hour) // Access token 2 小时有效期
 
 	accessSession := &SSOSession{
-		SessionID:  token,
-		UserID:     session.UserID,
-		Username:   session.Username,
-		ClientID:   clientID,
-		CreatedAt:  time.Now(),
-		ExpiresAt:  expiresAt,
-		Scope:      session.Scope,
+		SessionID: token,
+		UserID:    session.UserID,
+		Username:  session.Username,
+		ClientID:  clientID,
+		CreatedAt: time.Now(),
+		ExpiresAt: expiresAt,
+		Scope:     session.Scope,
 	}
 
 	m.mu.Lock()